During a typical installation of a window in a building, a rough opening is first prepared in a wall of the building for receiving the window. The rough opening is defined by two jambs that extend vertically from a head at the top of the rough opening to a sill at the bottom of the opening. A weather resistant barrier material, such as a thin sheet of waterproof paper or plastic can be disposed over the outer surface of the wall, and the barrier material is cut at the rough opening and folded into the opening. The barrier material forms a moisture barrier extending over the outer surface, but due to the cuts in the barrier material does not normally provide a waterproof barrier on the inner surfaces of the rough opening. In particular, the barrier typically defines openings at the intersection of the jambs and the sill. A sill flashing is often installed across the sill. The sill flashing extends outward from the sill onto a portion of the outer surface of the wall and upward from the sill onto a portion of each jamb. Thus, the sill flashing, which is formed of a flexible sheet of material, is cut and bent to correspond to the sill, jambs, and outer wall surface. Typically, two cuts are made in the sill flashing, each cut extending from a respective corner of the sill and the jambs through the portion of the sill flashing that is disposed on the outer surface of the wall. Similarly, flashing can be installed on each of the jambs and the head of the rough opening before the window is secured in the opening.
The window can be structured to prevent rain or other water contacting the outer surface of the window from flowing to the sill of the rough opening. However, in some cases, the window can leak water to the sill. Water flowing to the sill of the rough opening can sometimes penetrate both the barrier material and the flashing, e.g., through the cuts that are made in the barrier material and the flashing during installation. Thus, the water can flow into the wall, i.e., between the inner and outer surfaces of the wall, causing damage to the wall.
Thus, there exists a need for a device and method for use in a window installation for preventing the flow of water to the rough opening in the wall and to the inside of the wall. The device should be compatible with conventional windows and installation methods. Preferably, the device should be relatively easy to install and economical to manufacture.